Hydropneumatic prop



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.l f M w W W Y L m i 4 a b 6 m L JHM @a Filed March 19. 1962y H. LEDEEN 3,191,505 HYDROPNEUMATIC PROP '2 Sheets-Sheet 2 5i 1ra/5,' M7- June 29, 1965 Filed March 19. 1962 a Z w M y @3% @a IN VEN TOR.

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,WAPo ze B Y. A45 4r United States Patent 3,191,506 HYDRGPNEUMATIC PROP Howard Ledeen, La Canada, Calif., assigner to Letleen, lnc., El Monte, Calif., a corporation of California Filed Mar. 19, 1962, Ser. No. 189,591 6 Claims. (Cl. 91454) in for convenience with no intention of limiting it there- In general, the invention contemplates, and a primary object thereof is to provide, a hydropneumatic prop or stull which is both capable of yielding to any closing action tending to reduce the distance between the surfaces to be spaced apart, and of following in response to any opening action tending to increase the distance between such surfaces. The yielding action of the prop or stull of the invention is important for the obvious reason that it assures continued support despite any closing action of the ground, and accomplishes this without destruction of the prop, as long as the closing action does not exceed the operating range of the prop. The ability of the prop or stull of the invention to follow in the event of an opening action of the ground is important since it also insures continued support, again within the operating range of the prop. The foregoing is accomplished with the hydropneumatic prop of the invention by hydraulically actuating the prop and by providing it with an integral pneumatic accumulator. In accordance with my presently preferred construction, the prop or stull includes: a cylinder having fopen 4and closed ends; a tubular main piston projecting from the open end of the cylinder and having a closed -outer end and an inner end in fluid communication with the cylinder; an accumulator piston reciprocable in the tubular main piston; charging valve means for introducing a gas, such as nitrogen, under pressure into the main piston between the outer end thereof and the accumulator piston; and charging valve means for introducing a hydraulic fluid or liquid under pressure into the cylinder. With this construction, a very simple and compact hydropneumatic prop, capable of yielding to and following loads imposed thereon, results.

An important object of the invention is to provide a hydropneumatic prop usable as one component of a twocomponent modular support having as its other component an ordinary pipe which is telescopically connectible to the prop and which is of a length such as to enable the prop to operate as outlined above when one end of the pipe is in engagement with one surface and one end of the prop is in engagement with the opposed surface Vand is in an extended position. The advantage of this modular construction is that the hydropneumatic prop itself may be a relatively short unit which is cheaper to manufacture, lighter in weight and thus easier to handle, and the like. The pipe with which the prop is used may be cut to whatever length is necessary for the particular environment.

Another object of the invention is to provide a hydropneumatic prop one end, preferably the cylinder end, of which is insertable into one end of the pipe, the cylinder of the prop being provided thereon with external abutment means, e.g., an annular flange or shoulder, seatable on the corresponding end of the pipe to transfer compression loads to the pipe.

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A further object is to provide the outer end of the piston of the hydropneumatic prop with a supporting head engageable with one of the surfaces to be spaced apart, such as a mine timber seated against a roof surface to be supported. The lower end of the pipe may be provided with a suitable foot engageable with a floor surface, or may be seated against a mine timber on the floor surface.

An additional object of the invention .is to provide a hydropneumatic prop having a relatively small hydraulic fluid reservoir so that the prop can be energized or set by means of a simple portable hand pump, although powered pumping equipment may be used if desired. Preferably, the prop is pneumatically precharged, so that the operations of erecting and setting the modular support can be performed quickly and easily with only a pump for the hydraulic fluid.

A further important object of the invention is to provide `a hydropneumatic prop which is equipped with, or which may have readily connected thereto, a pressure gauge for measuring and indicating the pressure of the hydraulic fluid or liquid within the cylinder. By this mean, an indication of the load being carried by the prop is quickly available so that additional modular supports may be erected and set if conditions so dictate.

The hydropneumatic prop of the invention is equipped with a discharge valve means for discharging hydraulic huid from the cylinder whenever it is desired to collapse the prop in order to remove it. Preferably, the hydraulic fluid thus discharged is simply wasted, thereby avoiding any necessity for a large reservoir, and reducing the size and weight of the prop to make it lighter and more compact and thus easier to handle. The invention contemplates utilizing an inexpensive hydraulic uid, such as diesel fuel, fuel oil, or the like, so that the expense of replacing iluid wasted upon discharge is not a significant factor. l

Another and important object of the invention is to provide a hydr-opneumatic prop wherein the outlet of the discharge valve means is located radially inwardly of the external annular abutment means and communicates with the interior of the pipe when in use. Thus, any hydraulic fluid discharged in collapsing the prop is wasted into the pipe, thereby preventing any possibility of injury to personnel by a high velocity jet of fluid.

Another object is to provide a hydropneumatic prop which may be collapsed from a remote point, as in retreat mining, by a cable or rope lanyard connected thereto.

j Another object in connection with the foregoing is to utilize the lanyard for discharging hydraulic liuid from the prop as a means of pulling the prop to safety from a remote point so as to retrieve it. Thus, a single lanyard serves the purpose of collapsing the prop and of retrieving it. The pipe of the modular support may also be equipped with a cable or rope for purposes of retrieval.

Another important advantage, not heretofore mentioned, is that the integral pneumatic accumulator insures that the prop will always perform a supporting function, not only despite any opening action of the ground, but despite any leakage which may occur. In this connection, the direct load indication provided by a pressure gauge in communication with the cylinder of the prop serves `to call attention to any need for recharging the cylinder with hydraulic fluid, whether to compensate for any opening action of the ground, or for leakage.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in the propping art in the light of this disclosure, may be achieved with the exemplary embodiment of the invention described in detail herein- 3 after and illustrated in the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of a modular support of the invention incorporating a hydropneumati prop or stull thereof;

FIG. 2 is a transverse sectional view taken as indicated by the arrowed line 2 2 of FIG. l;

FIG. 3 is an enlarged, framentary longitudinal sectional View duplicating a portion of FlG. l, but illustrates various parts in other operating positions;

FIG. 4 is a semidiagrammatic, longitudinal sectional View illustrating the effect on the hydropneumatic prop of the invention of varying hydraulic pressure for a given initial accumulator pressure; and Y FIGS. 5, 6 and 7 are views similar to FIG. 4, but illustrate the yielding and following action of the hydropneumatic prop or stull of the invention.

Referring particularly to FIG. 1 of the drawings, v

particular environment is illustrative only, and that the Y i nected to the Charging Valve g in a Weipknown manner modular support 10 may be used in numerous other environments, and may be oriented horizontally, or at an angle, as well as vertically.

The modular support lil includes a hydropneumatic prop or stull 200i the invention telescoped into and seated Y ends with an external annular ange or collar constituting an external annular abutment means seatable on the upper end of the pipe 22 to transmit compression loads to the pipe. The annular tiange 30 is locatedV adjacent the upper end ofthe cylinder 26 to provide better column stability.

The outer or upper end of the cylinder 26 is open and secured therein is a liner 32 in which a tubular main piston 34 is reciprocable, suitable fluid tight seals being provided between the cylinder and the liner and between the liner and the tubular piston. The outer end of the tubular piston 34 projects from the outer end of the cylinder 26 and forms, in effect, a piston rod having connected thereto a supporting head 36 shown as seated against the mine timber 14. The supporting head 36 is suitably secured to the outer end of the tubular piston 34 and closes it in a fluid tight manner. The outer end of the supporting head 36 is serrated, or otherwise roughened, for gripping engagement with the mine timber 14.

The tubular piston 34 communicates at its inner end with the interior of the cylinder 26, both because of the fact that the inner end of the tubular piston is open, as shown, and because of the fact that it is provided with two diametrally opposed ports 38 adjacent its inner end. A transverse stop pin extends through the tubular piston 34 in substantially the plane of the ports 38, and is adapted to engage the inner end of the liner 32 to limit extension of the prop 20. Y

Reciprocable within the tubular piston 34 is an accumulator piston 42 suitably sealed relative to the tubular piston. The accumulator piston 42 is capable of movement throughout a range limited at its inner end by the stop pin 40 and at its outer end by the supporting head 36.

It will be noted that the accumulator piston 42 acts as a movable barrier between the 'portion of the tubular piston 34 therebeneath and the portion of the tubular piston thereabove. The portion of the tubular piston 34 above the accumulator piston 42 is precharged with a gas, such as nitrogen,under pressure so :that such portion of the tubular portion acts as a pneumatic accumulator 44. The latter is precharged through' a charging valve or valve means 45 of any suitable construction carried by the supporting head 36 and disposed in a central Well 48 therein. To protect the charging valve 46, the outer end of the well 48 is closed by a cover 50 suitably secured in place. This cover may be removed Whenever it is necessary to replenish the gas in the pneumatic accumulator 44. Once the pneumatic accumulator 44 has been precharged to a relatively high pressure, e.g., 1000 p.s.i., it is normally not necessary to replenish the gas as long as the various seals shown remain fluid tight.

The hydropneumatic prop 20 is energized by introducing hydraulic iiuid into the cylinder 26, a charging valve or valve means 52 disposed in a cavity 54 in the annular flange 36 being provided for this purpose. The charging valve S2 is of the inwardly-opening check valve type, being similar to an ordinary pneumatic tire valve. An outlet fitting of a hydraulic pump, not shown, may be conwhen charging of the prop 20 with hydraulic liuid is desired. As previously indicated, such hydraulic pump may be a simple hand operated pump since the hydraulic fluid capacity of the prop 2@ is small, although a powered pump may be used. When not in use, the charging valve 52 is protected by a cover S6 inserted into the well 48 and secured by a Set screw S8.

In order to measure the hydraulic iuid pressure in the hydropneumatic prop 2t? -to provide an indication of the load being carried, a pressure gaugeV 60, FIG. 4, may be applied to the charging valve 52, after removal of the cover 56, in much the same manner as a pneumatic tire inflation pressure gauge is applied to the valve of a pneumatic tire. Alternatively, :the hydropneurnatic prop 20 may be provided with a pressure gauge, not shown, permanently mounted on and in communication with the interior of the cylinder 26.

The hydropneumatic prop 20 of the invention also includes a discharge valve or valve means 62, shown as mounted on the annular iiangetl opposite the charging valve 52. The discharge valve means 62 provides an inlet 64 in communication with the interior of the cylinder 26 and an outlet 66 located radially inwardly of the annular supporting surface provided by the annular flange 30, and ldirected toward the inner end of the -cylinder 26. Thus,V when the discharge valve 62 is actuated to release the. prop 20, the necessary hydraulic iiuid is wasted into the pipe 22 to prevent possible injury to personnel by a high pressure liquid jet. As previously explained, an inexpensive hydraulic iiuid, such as diesel fuel, is used so that any wastage necessary in collapsing the prop 2t) is insignificant as respects operating costs.

The discharge valve 62 may be of any suitable construction, and preferably is of the inwardly-opening check Valve type so that it is maintained closed by the pressure of the hydraulic fluid within the cylinder 25. With this in mind, the discharge valve 62 is provided with a poppettype check valve 68, FIG. 3 biased outwardly into engagement with a valve seat 79 by internal pressure and by a spring 72.

The check valve 68 is adapted to be unseated by a plunger 74 biased away from the check valve by a spring 76, the plunger 74 being disposed in a housing '7S mounted on the annular flange 3G. The plunger 74 is displaced toward the check valve 68 to unseat it by a cam 80 mounted on a pivot pin 82 carried by the housing 78. The cam Si) is adapted to be rotated from an inoperative position, shown in FIG. l, to an operative position, shown in FG. 3, by a bifurcated handle 84 the arms of which are connected to the pivot pin 82. The handle 84 is adapted to be locked in its retracted position, corresponding to the inoperative position of the cam 80, by a cotter pin 86, FIG. l, or the like. Outward movement of the handle 84 is limited by a stop S8 in the form of a loop connected to the cylinder 26. The handle 84 may be manually actuated directly, or it may be remotely actuated by a cable or rope lanyard 90. In the construction illustrated, the lanyard 90 is shown as terminating in hooks 92 engageable with a transverse pin 94 forming part of the handle and connecting the two arms thereof.

Operation It will be assumed that the pneumatic accumulator 44 has been precharged prior to placing the hydropneumatic prop 20 in operation. Consequently, all that is required ofthe operator in erecting and setting the modular support 1t) is to cut or select a pipe 22 of the proper length, assemble the prop and the pipe in the manner illustrated, erect the resulting modular support with the mine timber 14 in place on the supporting head 36, connect a hydraulic pump to the charging valve 52,V and pump the prop up to the pressure necessary to achieve the desired loading. Thi-s pressure may be indicated by a guage on the hydraulic pump, or by applying the gauge 60 to the charging valve 52 after disconnecting the hydraulic pump therefrom.

As will be apparent, the higher the hydraulic pressure developed in the cylinder 26, the greater the supporting force provided by the hydropneumatic prop 20. FIG. 4 of the drawings illustrates semidiagrammatically the effect of varying the setting pressure for a constant distance between the floor 12 and the timber 14, or other surfaces to be spaced apart, and for a given initial accumulator pressure. The numeral 42 illustrates the position of the accumulator piston for a relatively low setting pressure, while the reference characters 42 and 42 respectively show the accumulator piston positions for intermediate and relatively high setting pressures. It will be understood, of course, that the accumulator piston 42 is not displaced outwardly away from the transverse stop pin 40 until such time as the setting pressure exceeds the initial accumulator pressure. Once the initial accumulator pressure is exceeded, further compression of the gas in the accumulator 44 occurs to equalize the pneumatic and hydraulic pressures.

FIGS. 5, 6 and 7 illustrate the energy storing spring" eiect of the pneumatic accumulator 44. More particularly, if FIG. 5 is regarded as illustrating an initial hydraulic charging or setting pressure such as to displace the accumulator piston 42 into an intermediate position, FIG. 6 illustrates the action of the hydropneumatic prop 26 in yielding to a closing action of the ground, and FIG. 7 illustrates the action of the prop in extending so as to follow in response to an opening action. Comparing FIG. 6 with FIG. 5, it will `be seen that, as a closing action occurs, the length of the hydropneumatic prop 20 is decreased, with a consequent increase in the compression of the gas within the pneumatic accumulator section 44. Under these conditions, the supported load is increased, as will be evident from a comparison of the lengths of the arrows 96 and 97. 0n the other hand, comparing FIG. 7 with FIG. 5, if an opening action occurs, the hydropneumatic prop 20 automatically extends and follows, and, at the same time, the gas in the pneumatic accumulator 44 expands with a consequent decrease in the supported load. The relative supported loads are evident from the relative lengths of the arrows 96 and 98.

Thus, the present invention provides continued support despite rvariations in the spacing of the supporting surfaces, the hydropneumatic prop 20 yielding in response to a decrease in such spacing, and following an increase therein.

When it is desired to remove the modular support 10, this can be done very simply by moving the discharge handle 84 into its extended position to actuate the discharge valve 62, the necessary discharge of hydraulic uid being directed into the pipe 22 to avoid injury to personnel 6 in the area. The modular support 10 can then be disassembled into its two basic components, the hydropneumatic prop 20 and the pipe 22.

In the event that releasing the hydropneumatic prop 20 by direct manual manipulation of the discharge handle 84 would be too hazardous, asin retreat mining likely to produce roof falls, the discharge handle may be moved into its extended position to actuate the discharge valve 62 from a remote point by means of the lanyard 90. As FIG. 3 of the drawings clearly suggests, once the handle 84 has been extended against the stop 88, a continued pull on the lanyard may be employed to drag the hydropneumatic prop 20 into a supported area. The pipe 22 may be retrieved in a similar manner by a cable or rope, not shown, suitably attached thereto.

The hydropneumatic prop 20 of the invention is quite compact and light in weight so that it can be handled easily by one man. For example, the hydropneumatic prop 20 of the invention may Weigh as little as 65 pounds for a load supporting capacity in the range of 15 tons, or more, which is an important feature.

Although an exemplary embodiment of the invention has been described herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiment departing from the spirit of the invention as defined by the claims which follow.

I claim:

1. In a two-component modular support yfor maintaining two opposed surfaces in space relation, the combination of:

(a) an extensible and contractible hydropneumatic prop including an end disengageably seated against one of said surfaces and including a duid-containing member having an annular abutment spaced from and facing away from said one end of said prop;

(b) said spacing of said one end of said prop and said annular abutment thereon varying as said prop is extended and contracted;

(c) a pipe separate from said duid-containing member, and of a length equal to the dilerence between the l spacing of said surfaces and said spacing of said one end of said prop and said annular abutment thereon when said prop is in an extended position;

(d) one end of said pipe being disengageably seated against the other of said surfaces;

(e) said annular abutment being disengageably seated against the other end of said pipe; and

(f) means for extending said prop into its said extended position to maintain said one end of said prop seated against said one surface, said one end of said pipe seated against said other surface, and said annular abutment seated against said other end of said pipe.

2. In an extensible and contractible hydropneumatic prop containing a liquid and a gas and usable with a pipe having an end engageable with one of two opposed surfaces to be maintained in spaced relation, the combination of (a) said prop including means at one end thereof engageable with the other of the surfaces;

(b) said prop including a liquid-containing member sepparate from the pipe and having thereon an annular abutment spaced from and facing away from said one end of said prop;

(c) said spacing of said one end of said prop and said annular abutment varying as said prop is extended and contracted;

(d) said annular abutment being disengageably seatable on the 'other end of the pipe; and

(e) means -for introducing liquid into said liquid-containing member to extend said prop.

3. In an extensible and contractible hydropneumatic prop containing a liquid and a gas and usable with a pipe having an end engageable with one of two opposed surfaces to be maintained in spaced relation, the combination of l (a) means on said prop at one end thereof engageable with the other of the surfaces; (b) an annular abutment on said prop and spaced from and facing away from said one end thereof; (c) said spacing of said one end of said prop and said annular abutment thereon varying as said prop is extended and contracted; (d) said annular abutment being disengageably seatable on the other end of the pipe;

(e) means for introducing liquid into said prop to extend same; (f) discharge valve means carried by said prop for discharging liquid from said prop to contract same; (g) said discharge valve means having an outlet within the contines of said annular abutment; and (h) whereby liquid from said prop is discharged into the pipe when said discharge valve means is opened with said annular abutment disengageably seated on said other end of the pipe.

4. In an extensible and contractible hydropneumatic prop containing a liquid and a gas and usable with a pipe having an end engageable with one of two opposed surfaces to be maintained in spaced relation, the combination of v (a) means on said prop at one end thereof engageable with the other of the surfaces;

(b) an annular abutment on said prop and spaced from (d) said annular abutment being disengageably seatable on the other end of the pipe;

(e) means for introducing liquid into said prop to extend same;

(f) discharge valve means carried by said prop for discharging liquid from said prop to contract same;

(g) said discharge Valve means having an outlet within the contines of said annular abutment;

(h) whereby liquid from said prop is discharged into the pipe when said dischargevalve means is opened with `said annular abutment disengageably seated on said other end Vof the pipe; and

(i) lanyard means operable from a remote 'point and connected'to said discharge valve means for actuating said discharge valve means and for simultaneously pulling said prop from between said other surface and said other end of the pipe.

5. In a hydropneumatic prop, the combination of:

(a) a cylinder member having open and closed ends;

' (b) a tubular main piston member reciprocable in said cylinder member;

(c) said main piston member having an inner end adjacent said closed end of and in huid communication with said cylinder member and including an outer end projecting axially from said open end of said cylinder member; (d) rst abutment meanson one of said members; (e) an accumulator piston reciprocable in said main piston member;

(f) charging valve means for introducing gas under pressure into said main piston member between the outer end thereof and said accumulator piston;

(g) charging valve means for introducing liquid under pressure into said Vcylinder member;

(h) second, annular abutment` means on the other of said members and facing away from said rst abutment means;

(i) discharge valve means carried by said prop and having an inlet communicating with the interior of said cylinder member and an outlet communicating with the exterior of said prop radially inwardly of said annular abutment means; and

(j) means for opening said discharge valve means.

6. In a hydropneumatic prop, the combination of:

(a) a cylinder member having open and closed ends;

(b) a tubular main piston member reciprocable in said cylinder member; Y

(c) said main piston member having an inner end adjacent said closed end of and in fluid communication with said cylinder member and including .an outer end projecting axially from said open end of said cylinder member;

(d) first abutment means on one of said members;

(e) an accumulator piston reciprocable in said main piston member;

(f) charging valve means for introducing gas under pressure into said main piston member between the outer end thereof and said accumulator piston;

(g) charging valve means for introducing liquid under pressure into said cylinder member;

(h) second, annular abutment means on the other of Said members and facing away from said yt'irst abutment means;

(i) discharge valve means carried by Vsaid prop and having an inlet communicating with the interior of said cylinder member and an outlet communicating with the exterior or" said prop radially inwardly of said annular abutment means; and

(j) means for opening said discharge Valve means and for simultaneously pulling said prop from one location to another.

References Cited by the Examiner UNITED STATES PATENTS 1,898,694 2/33 Sikorsky 121-46 2,165,095 7/39 Frechette 121-46 2,192,909 3/4-0 Hotfar 121-46 2,337,573 12/43 Schultz 121-46 2,695,764 11/54 Grebe 121-46 2,778,627 1/57 Sands 121-46 2,891,635 6/59 Joseph 121-46 2,951,558 9/60 Schuster 121-38 2,994,301 8/61 Kirsch 121-2 3,032,016 5/62 Smith 121-46 3,042,149 7/62 Comfort 121-46 3,065,738 11/62 Loughridge 121-46 'K0 FRED n. ENGELTHALER, Primary Examiner.

RICHARD B. WILKINSON, SAMUEL LnvrNE,

Examiners, 

1. IN A TWO-COMPONENT MODULAR SUPPORT FOR MAINTAINING TWO OPPOSED SURFACES IN SPACE RELATION, TO COMBINATION OF: (A) AN EXTENSIBLE AND CONTRACIBLE HYDROPNEUMATIC PROP INCLUDING AN END DISENGAGEABLY SEATED AGAINST ONE OF SAID SURFACES AND INCLUDING A FLUID-CONTAINING MEMBER HAVING AN ANNULAR ABUTMENT SPACED FROM AND FACING AWAY FROM SAID END OF SAID PROP; (B) SAID SPACING OF SAID ONE END OF SAID PROP AND SAID ANNULAR ABUTMENT THEREON VARYING AS SAID PROP IS EXTENDED AND CONTRACTED; (C) A PIPE SEPARATE FROM SAID FLUID-CONTAINING MEMBER, AND OF A LENGTH EQUAL TO THE DIFFERENCE BETWEEN THE SPACING OF SAID SURFACES AND SAID SPACING OF SAID ONE END OF SAID PROP AND SAID ANNULAR ABUTMENT THEREON WHEN SAID PROP IS AN EXTENDED POSITION; (D) ONE END OF SAID PIPE BEING DISENGAGEABLY SEATED AGAINST THE OTHER END OF SAID SURFACES; (E) SAID ANNULAR ABUTMENT BEING DISENGAGEABLY SEATED AGAINST THE OTHER END OF SAID PIPE; AND (F) MEANS FOR EXTENDING SAID PROP INTO ITS SAID EXTENDED POSITION TO MAINTAIN SAID ONE END OF SAID PROP SEATED AGAINST SAID ONE SURFACE, SAID ONE END OF SAID PIPE SEATED AGAINST SAID OTHER, AND SAID ANNULAR ABUTMENT SEATED AGAINST SAID OTHER END OF SAID PIPE. 